In the proposed work, children's competence is studied in grammatical constructions in which they already display some stable competence of use. The two chief constructions being studied are in conjunction with the coordinate particle and and the passive construction in English. In the case of conjunction, study is of two chief problems. 1) Children's early conjunctions of predicate phrases are largely of the form actional VP and actional VP. Actions such as push and make are distinguished here from statives such as know and have. VPs such as push the dog or know the answer are distinguished from Copula phrases such as is a dog or is happy. Adult conjunctions of phrases such as NPs are limited by semantic similarity, but predicate conjunctions are not. The purpose of the study is to see whether children's initial limitation of use to semantically and structurally similar VPs is a matter of underlying competence or of sampling and pragmatic factors. To this point, children are given conjunctions in stories which mix both semantic and syntactic predicate phrases of conjunctions. 2) Children's initial conjunctions make use of NP, VP, and S conjunction. The major category not used is Verb conjunction. Children are given sentences with verb conjunction to imitate. In the case of passive, the central problem is the following: four- and five-year old English-speaking children seem to comprehend actional passives such as The boy was tickled by the girl. But the English passive relates a wide variety of sentence types regardless of the semantics of the verb, such as the boy was liked by the girl, which is not an actional passive, but a stative one. In the present research, children are tested by a questioning procedure for their comprehension of stative passives, given that they comprehend actional ones in the same procedure, to investigate whether their initial stable comprehension of passives is limited to correspondence of phrase structure and semantic categories rather than being a syntactically general relation of passive and active sentences across semantic categories.